We've been using Nitek. They have a couple of configurations we haven't seen elsewhere, and they have some nice rack-mount concentrator stuff too.

We just added 5 new cameras to a big steelyard here. All 5 cameras to a central point with a power supply and a 66 block, then a couple of CAT5 "busses" back to security. Worked like a champ and saved us a ton of coax. Try THAT with RG59!